Patent GB-792805-A (GB)
Title: Improvements in the manufacture of voluminous artificial yarns
Inventor: GROOMBRIDGE DENIS WILLIAM
IPC: D01D5/04
Filed: 1954-11-16
Abstract: A process for the manufacture of voluminous artificial yarns comprises (1) forming crinkled filaments by extruding a solution of a filamentforming substance in a volatile solvent into an evaporative atmosphere at a linear rate which is substantially higher than the maximum speed at which the solution immediately after extrusion, and the filaments formed from it, while they are still travelling freely through the evaporative atmosphere, will tend to travel under the influence of the various forces acting on them; (2) doubling the crinkled filaments with a substantially uncrinkled support thread; and (3) collecting the resulting compound thread at such a speed that substantially no tension is exerted thereby on the crinkled filaments before they make contact with the support thread or are collected. Preferably the crinkled filaments are brought into contact with the support thread during their travel from the spinning jet by means of which they are formed and before they are collected or taken up.  The crinkled filaments and the support thread may be chemically similar or different.  Thus, they may both have a basis of a cellulose ester of a fatty acid containing up to 4 carbon atoms in the molecule, e.g. an acetone-soluble cellulose acetate or a cellulose triacetate, or of a polymer or copolymer of acrylonitrile, vinyl chloride or another vinyl compound.  Alternatively, crinkled filaments of cellulose acetate may be doubled with a regenerated cellulose support thread made either by the viscose process or by the saponification of a cellulose acetate yarn that has been stretched while in a softened condition.  The support thread may also be made of a high linear polyamide or polyester, especially a polyamide derived from amino-caproic acid or from adipic acid and hexamethylene diamine, or a polyester derived from ethylene glycol and terephthalic acid.  The crinkled filaments and the support thread may be formed simultaneously in a single dry-spinning cell or the crinkled filaments may be doubled with a preformed support thread.  In both methods the crinkled filaments are preferably brought into contact with the support thread in the spinning cell in which they are made. In an example, a solution of cellulose acetate in acetone at 60 DEG C. is fed at equal volume rates of flow to two spinning jets, by one of which crinkled filaments are formed and by the other of which a support thread is formed.  The spinning jets are arranged side by side at the top of a dryspinning cell, the wall of which is heated to 67 DEG  C.  The crinkled filaments and the support thread are drawn out of the lower portion of the cell as a single combined yarn by means of a draw roll, and are then simultaneously wound up and given a twist of 2.5 turns per inch by means of a cap spinner.  The product is a voluminous yarn of denier 600, having a very soft handle.  In another example, instead of forming the support thread in the cell, a preformed cellulose acetate thread of zero twist is drawn from a package down through the cell and combined with crinkled filaments produced as described in the previous example.  In a third example, a solution of cellulose acetate in acetone at 60 DEG  C. is extruded through two identical spinning jets, the solution being fed 4 times as fast to the jet producing the crinkled filaments as to the other jet producing the support thread.  The crinkled filaments and the support thread are drawn from the cell as a single combined yarn as in the first example.  Spinning orifices having cross-sections other than circular, e.g. of slot or crescentshape, may be used, especially for spinning the crinkled filaments, and the composite yarns obtained may be boiled in water or aqueous soap solutions to modify their appearance. More than one support thread may be used, e.g. a second support thread may be brought into contact with the yarn already formed from the crinkled filaments and the first support thread, preferably before it is twisted.  The composite yarns produced may be passed sharply under tension round one or more guides to cause some or all of the crinkled filaments to break at intervals and give the yarn the appearance of having been spun from staple fibre.